The Department of Foreign Affairs (DFA) is advising Irish citizens to "exercise extreme caution" in Belgium.

Is it safe to travel?

UPDATE: On November 26, the DFA dropped its Security Status level for Belgium, warning Irish citizens to "exercise caution" in the country.

Irish citizens in Belgium are advised to be vigilant and to follow the advice of the Belgian authorities, according to the DFA's latest travel advice.

"There is an increased threat from terrorism," it says. "The utmost caution is advised at all times, especially at airports and train stations."

The advice follows the November 13 terrorist attacks in Paris, related raids in Brussels, and Belgium's escalation of the threat level in its capital to the maximum (level 4) - indicating that an attack in the capital remains "serious and imminent".

This level has now been extended to November 30 for the capital, with the rest of the country on alert level 3 (i.e. a terrorist attack is deemed "possible and real").

The public are allowed outdoors, but Belgian authorities are advising they avoid crowded places, and respect any security checks.

Yes. Aer Lingus and Ryanair, which fly from Dublin to Brussels Airport and Brussels S. Charleroi respectively, are operating as normal.

Zaventem Airport is not involved in level 4. enhanced safety measures were taken in the context of the level 3, but this has no impact on air traffic.

Passengers should expect delays due to increased security and the disruption to travel links, as well as the tightening of border controls with France.

I’m nervous about travel. Can I get a refund?

No. If you cancel your holiday without the DFA (dfa.ie/travel) declaring travel to be unsafe, it could be deemed "disinclination to travel".

As such, you may have to pay a cancellation fee or forfeit some or all of the cost of your air fare or holiday package.

That said, it's worth noting that Irish tour operators have in the past worked to facilitate customers affected by exceptional events, so it's always worth a phone call - particularly if you have booked a package that centres around the closed attractions.

The Brussels metro remains closed on Tuesday, November 24. "A gradual reopening is planned for Wednesday," according to its website, stib-mivb.be.

Schools remain closed until Wednesday, November 25.

Museums and cultural institutions, including the Royal Museums of Art and History and the Horta Museum and Atomium are closed Monday (see brusselsmuseums.be for updates).

Public and sporting events were cancelled this weekend, although The Davis Cup tennis final between Great Britain and Belgium remains scheduled for this weekend.

There is a heavy military and police presence at transport hubs and public sites.

What about trains?

Eurostar (eurostar.com) trains are operating as normal to and from Brussels, but is currently offering customers travelling up to and including Wednesday the chance to postpone their trip within 60 days, free of charge.

Customers are advised to allow for additional time to check in and complete security checks before travel.